Layered-Type Antiferromagnetic State in Double-Layered Manganites: (La_1-zNd_z)_2-2xSr_1+2xMn₂O₇

Abstract

Anisotropic magnetic and transport properties have been investigated for single crystals of layered-perovskite manganites (La_1-zNd_z)_2-2xSr_1+2xMn₂O₇ as a function of thendoping level x and averaged ionic radius z of the rare-earth ion.The ferromagnetic metallic (FM) state observed in La_1.2Sr_1.8Mn₂O₇ (x=0.4; z=0.0) disappears with increasing x or z, and the ground state is replaced by a layered antiferromagnetic (layered-AF) state beyond x-- 0.5. Thus obtained phase diagram is discussed in terms of variation of the e_g-band structure with the band-filling (=1-x).